A band of snow is moving across high ground in northern England in a brief return to wintry conditions – but forecasters do not see an end to the current and unusually mild weather in most of the UK.

Brighter skies are due to follow the cold front, which briefly threatened to close some roads but is now turning into rain in most of the affected areas of the north Pennines and the Scottish lowlands.

A large yellow lozenge is inching across the Met Office's severe weather warnings map, indicating the lowest state of alert – "be aware".

Forecasters warned that snow could still fall as far south as the Peak District before midday, with the risk of icy roads extending further towards Birmingham and the Wash on the east coast.

Milder but sometimes brisk weather is likely for the rest of the week, but the longer-term outlook continues to make frequent use of the word uncertain. Although a nasty delayed shock is not expected, older weather watchers recall that the severest winter of modern times, in 1947, did not begin in earnest until late January.

The Met Office is hedging its bets for early February, saying: "There appear to be two main scenarios, each equally probable, but which are very different."

"The first consists of a changeable westerly or southwesterly weather type with rain at times and with temperatures noticeably above average for early February, with only occasional frosts.

"The alternative is that much colder weather with winds mainly from an easterly or northeasterly quarter, will prevail well into February, bringing widespread frosts and snow to some areas. In this scenario, it would be the east that was most vulnerable to snowfall."

Temperatures have meanwhile risen above freezing in most of Scotland including Inverness, where 16-year-old Scott Campbell was found dead in a garden near his home after a night out.

Friends said that he was thought to have been overcome by freezing temperatures after last being seen at 5.15am.

A woman who was rescued from Whitehaven harbour, in Cumbria, has died in hospital. She was carried unconscious from the icy water by police officers, resuscitated and taken to west Cumberland hospital in the town, after passersby raised the alarm at 2pm on Monday.

Her identity will not be released until her relatives have been informed.

The windy conditions that swept across much of northern England on Monday have died away, but the National Express East Anglia rail company blamed a poor punctuality performance in early January on repeated gusts of wind slowing down trains.

Meanwhile, in Cornwall the trend of banana plants flowering months early and spring flowers appearing at Christmas was continuing, with reports of butterflies emerging from chrysalises or hibernation.

Villagers in Badgall and Laneast are taking no chances, however, after being cut off for a week by a blizzard last year. They have bought their own snowplough and salt-spreader after raising £2,650.

At the Hawk Conservancy in Andover, Hampshire, a pair of white-backed vultures from southern Africa have nested and the female is thought to be sitting on an egg.